It is widely practiced that a test subject, such as a food or a pharmaceutical product, is irradiated with X-rays, and inspected for presence or absence of a foreign matter in the subject from a transmitted X-ray image thereof. An X-ray detection device that includes a line sensor for detecting a transmission image by X-rays emitted from an X-ray source toward the subject is used for the inspection. The X-ray detection device adopts, for example, a configuration where two line sensors are arranged in parallel in such a way as to detect X-rays in different energy ranges, in a case where foreign matters to be detected are different (for example, whether the foreign matter is a piece of bone or metal included in meat) (for example, see Patent Literature 1). In the X-ray detection device described in Patent Literature 1, a radiation quality variable body is provided on one sensor to vary the radiation qualities of the X-rays to reach the line sensors.